perf(sni): eliminate icon theme rescanning from system tray hotpath

Valgrind Massif profiling revealed that invoking Gtk::IconTheme::rescan_if_needed() inside SNI updateImage() and getIconByName() loops caused considerable memory churn and potential filesystem stat overhead whenever a system tray app pushed a metadata update.

This commit removes the rescan polling from the SNI proxy callback pipeline and the DefaultGtkIconThemeWrapper, restricting icon theme caching to load boundaries.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

src/modules/sni/item.cpp

@@ -423,8 +423,6 @@ Glib::RefPtr<Gdk::Pixbuf> Item::getIconPixbuf() {
 }
 
 Glib::RefPtr<Gdk::Pixbuf> Item::getIconByName(const std::string& name, int request_size) {
-  icon_theme->rescan_if_needed();
-
   if (!icon_theme_path.empty()) {
     auto icon_info = icon_theme->lookup_icon(name.c_str(), request_size,
                                              Gtk::IconLookupFlags::ICON_LOOKUP_FORCE_SIZE);

src/util/gtk_icon.cpp

@@ -21,7 +21,6 @@ Glib::RefPtr<Gdk::Pixbuf> DefaultGtkIconThemeWrapper::load_icon(
   const std::lock_guard<std::mutex> lock(default_theme_mutex);
 
   auto default_theme = Gtk::IconTheme::get_default();
-  default_theme->rescan_if_needed();
 
   auto icon_info = default_theme->lookup_icon(name, tmp_size, flags);